On 29 September 1990, Imanol made his first-team – and La Liga – debut, playing the full 90 minutes in a 2–1 away loss against Real Oviedo.

[3] He was used rarely in the final years of his stint at the Anoeta Stadium as he dealt with several injury problems, leaving the club in 1998 after playing only four matches during the season.

[13] In the summer of 2018, Alguacil returned to the reserves and Asier Garitano took over the senior role,[14] but in December of the same year the latter was dismissed following a poor sequence of results and the former again became the first team coach.

[16] Alguacil led Real to their first trophy since 1987 on 3 April 2021, with a 1–0 victory against Basque rivals Athletic Bilbao in the 2020 Copa del Rey final (postponed due to the COVID-19 pandemic).

[21] With a fourth-place finish, he secured a fourth consecutive European season, and the side's first in the UEFA Champions League for a decade.